Hi All, New to Minitruck world, I bought a 1990 Hijet s83 climber 2 months ago and begin to work on it. Bought it for off road riding. I have redone the brakes, new spark plug and distributor, oil change etc. The problem I have is when the engine doesn't start fast and the engine is cranked for 5 to 10 seconds; coolant is pushed in the overflow tank ( I can hear a lot of bubbles in the overflow tank) and air is pushed in the radiator. If I crank it without radiator cap, coolant will squirt out. I suspect a bad head gasket ( or cracked head). However, as soon the engine is running, all seems to be OK. No more bubbles. I let it run for a while with heater full on and use a funnel to completely fill the radiator to remove air pocket. But any time I have to crank the engine for a long time , coolant will be pushed out and air will come back in the radiator. After this happen, if I remove radiator cap and put back the coolant in the radiator while the engine is running and let it run, all is fine. Engine is not overheating, no coolant in oil, no white smoke coming out of the exhaust. Radiator cap has been replaced, no coolant leak. However the coolant seem to become a little 'oily'. When this happen, if I don't put back the coolant in the radiator, pressure will still be in the radiator the next day. I can see it when I remove the radiator cap. I would have thought that when the engine is running with a bad head gasket the bubbles will be a lot more present compare to when we crank the engine. Any thoughts or comments will be greatly appreciated. Heand gasket is on order but it doen't seems to be an easy job to replace it... :-(
You definitely have an issue. I’d recommend either a bleed down test, or pressure testing the cooling system to pinpoint the issue before you tear it down. But, I’m pretty sure you’ll find an abladed spot on the cylinder head. I’d recommend pulling off the bed, not hard with a partner. It gives you a lot more access. The other option is to drop the engine and tranny out the bottom.
Update: Did some more test before attempting to change the head gasket. I wanted to know which cylinder was building pressure in the rad. Remove the spark plugs and did a compression test. 125-130-125. Then put a spark plug on cylinder 1, disconnect the coil and crank the engine. At every stroke I could see pressure coming in the rad. Try with cylinder 2 and had the same thing. Try with cylinder 3 and had the exact same thing, pressure building uo at every stroke.... :-( I decided to remove the valve cover and check the head bolts torquing. Retorque the 8 bolts to the specs following the pattern in the manual. 5 out of 8 were not torque properly> I was anxious to see if it would make many difference. Put back the valve cover and plugs and crank the engine without the coil for a long time. No more pressure building up in the radiator. Connect the coil wire and start the engine. All seems fine now.
Pleb, That's pretty interesting, as I could think of a lot of different issues that it could have been, starting with Jigs suggestions, and going from there. I like how you tackled it, and I'm glad that you found it! I was wondering if your unit ever had the cooling system flushed, and or cleaned? I did mine, and you wouldn't even believe the dirty, corrosion colored water, coolant, fluid that came out! Besides all the particles, that it removed from the side walls of the block! It really was pretty nasty! I know that was the first time mine was ever done! If you think about it, that stuff sits in there a long time, under hot and cold, varying temps, growing all kinds of cultured samples of whatever! Mine was in there 30 yrs.! Good Luck! Limestone
